Dispatch

The trick is in the fallback. Most conditional removal punishes you for missing the condition by doing nothing, but here the floor is a Twiddle that actually matters: tapping a blocker before an alpha strike, or stalling an attacker for a turn, even when your board has only one or two artifacts in play. When the metalcraft clause is live, the same single white mana becomes the cleanest answer the color owns: unconditional exile that ignores indestructible, regeneration, and death triggers, with none of the combat-status gating white removal usually leans on. White's cheap answers almost always ask the creature to be attacking or blocking, or hand the opponent compensation in life or lands; this one asks for none of that once the gate is met. That gap between the two modes is the whole design. White has rarely been allowed clean, cheap, unconditional removal without a steep gate or a tradeoff, and the artifact count is the gate doing its job: it ties the spell's full power to a board state you have to commit to building rather than handing it out for free. In a deck assembling artifacts anyway, three is a threshold you cross early and then never look back; the metalcraft text stops being a condition and starts being a default, and a one-mana instant that exiles anything is a rate white practically never sees. Outside that shell it degrades gracefully into a tempo play, which is exactly why it reads as honest rather than greedy.